## Abstract / Description of output

Using archival X-ray observations and a log-normal population model, we
estimate constraints on the intrinsic scatter in halo mass at fixed
optical richness for a galaxy cluster sample identified in Dark Energy
Survey Year-One (DES-Y1) data with the redMaPPer algorithm. We examine
the scaling behavior of X-ray temperatures,

*T*, with optical richness, λ_{X}_{RM}, for clusters in the redshift range 0.2 <*z*< 0.7. X-ray temperatures are obtained from*Chandra*and*XMM*observations for 58 and 110 redMaPPer systems, respectively. Despite non-uniform sky coverage, the*T*measurements are >50% complete for clusters with λ_{X}_{RM}> 130. Regression analysis on the two samples produces consistent posterior scaling parameters, from which we derive a combined constraint on the residual scatter, σ_{ln T | λ}= 0.275 ± 0.019. Joined with constraints for*T*scaling with halo mass from the Weighing the Giants program and richness–temperature covariance estimates from the LoCuSS sample, we derive the richness-conditioned scatter in mass, σ_{X}_{ln M | λ}= 0.30 ± 0.04_{(stat)}± 0.09_{(sys)},, at an optical richness of approximately 100. Uncertainties in external parameters, particularly the slope and variance of the*T*–mass relation and the covariance of_{X}*T*and λ_{X}_{RM}at fixed mass, dominate the systematic error. The 95% confidence region from joint sample analysis is relatively broad, σ_{ln M | λ}∈ [0.14, 0.55], or a factor ten in variance.Original language | English |
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Number of pages | 14 |

Journal | Monthly Notices of the Royal Astronomical Society |

DOIs | |

Publication status | Published - 26 Sept 2019 |

## Keywords / Materials (for Non-textual outputs)

- astro-ph.CO
- astro-ph.GA